1. Field of the Invention
The invention relates to the field of position control systems, and in particular to a compressed air control system adapted for controlling the supply of compressed air to an aircushion.
2. Prior Art
A compressed air control system is known from U.S. Pat. No. 3,648,799--Young et al in which a control unit opens and closes a pressure regulator in response to a position-sensing transmitter. The sensing and control mechanism according to that publication is sensitive to pressure fluctuations leading to a fluttering of the aircushion, and an automatically-controlled valve reduces the pressure supplied to the cushion until a stable condition is obtained once again.
U.S. Pat. No. 3,994,540--Petersen teaches a pressure compensating frame which controls the pressure supplied to the aircushions in response to sensed distance from a gliding surface such as a floor.
The present invention is adapted not only to control the air supply to the aircushions in response to the distance from a gliding surface, but also to do so in a manner that is free from oscillations, as well as responsive to differences in load and differences in roughness of the gliding surface.